1. Field of the Invention
The present invention relates to improvements in a glass arrangement such as a laminated glass including a polarization-direction changing film, and more particularly to such a laminated glass to be used in a head-up display system which is configured, for example, such that a driver of an automotive vehicle can observe an image of driving information projected as displaying light on a windshield glass while looking a frontal view through the windshield glass in such a manner that the vehicular information is superimposed on the frontal view.
2. Description of the Prior Art
A variety of glass arrangements have been hitherto proposed and put into practical use for a head-up display system of an automotive vehicle. The glass arrangements include those of the type using a film functioning as a half mirror. These glass arrangements are configured by directly applying the half mirror on a windshield glass, or by interposing the half mirror between two glass plates. However, with these glass arrangements, reflection of light of an image is unavoidably made on the front-side or rear-side surface of the glass plate thereby forming a double image which is difficult to be observed by a driver. In view of this, the glass arrangements of another type have been proposed, in which light of the image is reflected from the surface of the glass plate without using the half mirror in order to avoid formation of the double image. One of these is configured by applying a so-called .lambda./2 film (for changing a direction of polarization of light) as disclosed in Japanese Patent Provisional Publication No. 2-141720. Another one is configured by bonding a transparent film having birefringence on a transparent plate, as disclosed in Japanese Patent Provisional Publication No. 2-294615. A further one is configured by bonding a polarization-direction changing film on a transparent plate, as disclosed in Japanese Patent Provisional Publication No. 6-40271. However, such conventional glass arrangements are insufficient in impact resistance and penetration resistance so that they cannot meet the requirements of the impact and penetration resistances according to safety regulations such as JIS (Japanese Industrial Standard) No. R3211 (Automotive Vehicle Safety Glass) and R3212 (Automotive Vehicle Safety Class Testing Method).